Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces torque. Air flow into a spark-ignition engine is regulated via an operator-controllable throttle, and fuel flow is controlled to achieve an air/fuel ratio that is responsive to an operate request for power. Turbocharged engines pressurize air that is drawn into an intake manifold. Thus, a pressure difference may exist between the air in the intake manifold, i.e., pre-combustion and exhaust gas in an exhaust manifold, i.e. post-combustion. For example, the intake manifold pressure may be higher than the exhaust manifold pressure.
Engines that include variable cam phasing and/or variable valve control may selectively open intake and exhaust valves. For example only, an engine may selectively open intake and exhaust valves via cam phasers or energized solenoids. Opening intake and exhaust valves simultaneously in a turbocharged engine may allow higher pressure air in the intake manifold to flow through the cylinder towards the lower pressure exhaust gas in the exhaust manifold.